The Cook County Jail in Chicago has emerged as the worst epicenter of coronavirus spread in the country, The New York Times reports. At least 353 cases—238 inmates and 115 staff—can be traced to the facility, according to the Cook County Sheriff’s Office. The office had earlier released higher figures but later revised them down. Most of the 5,000 inmates there have not been tested, increasing the likelihood that the number of confirmed cases will rise in coming days. The jail had just two positive cases in late March, according to the Times. Experts predicted that, as the coronavirus pandemic worsened, the U.S.’s crowded jails would become uncontrollable vectors of the disease. The Bureau of Prisons began quarantining inmates across the country to their cells for two weeks April 1.